Substrate processing, such as the formation of magnetic disks, is a complex and complicated process. Large, customized equipment is required to carry out the numerous unique steps of coating a substrate with multiple layers, then heating and cooling the substrate. Machines for processing substrates usually have a large footprint, and require a significant amount of space to operate. Additionally, the machines need to be operated in high-tech clean rooms, which are expensive to build and maintain. Therefore, it is advantageous to reduce the overall footprint of the substrate processing machines.
It is also desired to improve the processing speed at which each substrate unit is fabricated so as to maximize the value of the equipment. Improving the processing speed is somewhat challenging, since many processing steps have a minimum required time that a particular coating must be applied, heated, or cooled in order to properly coat a substrate. Many improvements have therefore focused on the steps in the process that add no value, such as the time required to move a substrate from one step to the next.
To this end, current technology, such as the 200 Lean® system manufactured by Intevac, Inc. of Santa Clara, Calif., has developed numerous solutions to reduce the overall footprint of the machine. The 200 Lean® is described in further detail in U.S. Pat. No. 6,919,001 (hereafter “the '001 patent”), the disclosure of which is incorporated herein in its entirety. One improvement is the stackable configuration of processing chambers, which allows for double the amount of steps to be performed in half the space required previously. To move a substrate from one stack of processing chambers to another, elevators are configured on either side of the system to move the substrate once it reaches the end of one stack of chambers. Numerous other improvements, not relevant to this discussion, are also described in the '001 patent.
International Patent Publication No. WO 2006/026886 A1 (hereafter “the '886 publication”) also describes a substrate processing system with two stacks of processing chambers. Much like the 200 Lean® system described in the '001 patent, the '886 publication describes a lift module to transport a substrate from one stack to the next, and the use of magnetic means, i.e., linear motor, for the transport of the substrate carriers.
The movement of the substrate through a substrate processing system, such as those described in the '001 patent and '886 publication, also require the use of a carrier to support the substrate as it moves through the chambers. The carrier must be designed to tightly grip only the outer edges of the substrate, so as not to interfere with the coating processes. As a result, the carrier has a somewhat flimsy hold on the substrate. A slight bump to the carrier from any direction could knock the substrate out of the carrier, requiring the entire machine to be stopped and serviced. It is therefore desirable to minimize any turbulence on the carrier as it passes through the substrate processing system. Notably, acceleration forces in the direction perpendicular to the surface of the substrate must be minimized. However, this concern must be balanced with the need to improve processing speed, since the faster the process moves, the more likely it is for quick movements to knock the substrate off its carrier.
Therefore, what is needed is an improved substrate processing system that minimizes processing time for non-value added activities, prevents turbulence on the carrier and substrate, and simplifies the process of moving the substrate between multiple levels in a stackable system.